Interleukin-1 Biology
Interleukin-1 (IL-1) is a potent pro-inflammatory cytokine that can be produced by a variety of cell types, including mononuclear phagocytes, in response to infection and inflammation. The IL-1 family consists of seven agonists, including IL-1α and IL-1β, and three naturally occurring receptor antagonists, including the IL-1 receptor antagonist (IL-1Ra) (Dinarello, C A, Blood 1996, 87(6): 2095-147). Two IL-1 receptors, IL-1R type I and IL-1R type II, have been identified. Both receptors can interact with all three forms of the IL-1 family molecules. IL-1R1 is responsible for mediating IL-1-induced cellular activation. However, the IL-1/IL-1RI complex cannot signal by itself, but is dependent on association with a second receptor chain, IL-1R Accessory Protein (IL1RAP) (Dinarello, C A, Blood 1996, 87(6): 2095-147). In contrast to IL-1RI, IL-1RII does not induce cellular activation upon binding to IL-1 and thus IL-1RII functions as regulatory decoy receptor, leading to a net decrease in IL-1 available to bind to IL-1RI.
In addition to IL1-signaling, IL1RAP is critical for mediating the effects of IL-33, through the ST2/IL1RAP complex, and IL36, through the IL1Rrp2/IL1RAP complex (Garlanda et al., Immunity. 2013 Dec. 12; 39(6):1003-18)
IL-1 is a potent pro-inflammatory cytokine, which is induced at sites of local infection or inflammation and is involved in the regulation of a variety of physiological and cellular events (summarised in Dinarello C A, CHEST, 2000, 118: 503-508 and Dinarello, C A, Clin Exp Rheumatol, 2002, 20(5 Suppl 27): S1-13). It is capable of activating several cell types including leukocytes and endothelial cells. IL-1 induces and amplifies immunological responses by promoting the production and expression of adhesion molecules, cytokines, chemokines and other inflammatory mediators such as prostaglandin E2 and nitric oxide (NO). As a consequence, local inflammation is amplified and sustained. In addition, the IL-1-induced production of inflammatory mediators results in fever, headache, hypotension and weight loss. Furthermore, IL-1 is a hematopoietic growth factor and has been shown to reduce the nadir of leukocytes and platelets in patients during bone marrow transplantation. IL-1 has also been shown to promote angiogenesis by inducing the production of vascular endothelial growth factor, thereby promoting pannus formation and blood supply in rheumatic joints. Finally, IL-1 has been shown to promote the bone and cartilage degradation in rheumatic diseases.
The Role of IL-1 in Disease
IL-1 is implicated in a wide range of diseases and conditions ranging from gout to cancer (for reviews, see Dinarello et al., 2012, Nature Reviews 11:633-652 and Dinarello, 2014, Mol. Med. 20(suppl. 1):S43-S58; the disclosures of which are incorporated herein by reference), including:                Joint, bone and muscle diseases, such as rheumatoid arthritis and osteoarthritis;        Hereditary systemic autoinflammatory diseases, such as familial Mediterranean fever;        Systemic autoinflammatory diseases, such as systemic juvenile idiopathic arthritis and adult-onset Still's disease;        Common inflammatory diseases, such as gout and type 2 diabetes;        Acute-onset ischemic diseases, such as myocardial infarction; and        Cancer.        
A number of therapies for blocking IL-1 activity are approved and in development. Targeting IL-1 began in 1993 with the introduction of anakinra (Kineret; Amgen), a recombinant form of the naturally occurring IL-1 receptor antagonist (IL-Ra), which blocks the activity of both IL-1α and IL-1β; this therapeutic has since been used to demonstrate a role for IL-1 in numerous diseases (see above). Anakinra currently dominates the field of IL-1 therapeutics owing to its good safety record, short half-life and multiple routes of administration. Neutralising IL-1 with antibodies or soluble receptors has also proved to be effective, and the soluble decoy receptor rilonacept (Arcalyst; Regeneron) and the anti-IL-1β neutralizing monoclonal antibody canakinumab (Ilaris; Novartis) have now been approved for certain rare genetic conditions, such cryopyrin-associated periodic syndromes (CAPS). Other therapeutic approaches, including IL-1α neutralisation, a therapeutic vaccine targeting IL-1β and a chimaeric IL-1Ra, are in early clinical trials. In addition, orally active small-molecule inhibitors of IL-1 production, such as caspase 1 inhibitors, have been developed and are being tested.
Interleukin-33 (IL-33) is a nuclear-associated cytokine of the IL-1 family. IL-33 signals via the receptor IL-33R (ST2) and plays an important role in allergy, asthma, infections, inflammation, and in promoting cancer growth (see Cayrol & Girard (2014) Curr Opin Immunol. 31:31-7 and Maywald et al. (2015) PNAS 112(19):E2487-2496). IL1RAP is critical part of the IL-33R (ST2) receptor complex to convey the signals by IL-33 (see Chackerian et al. (2007) J Immunol. 179(4):2551-2555).
IL1RAP as a Biomarker for Neoplastic Disorders
Tumour biomarkers are endogenous proteins or metabolites whose amounts or modifications are indicative of tumour state, progression characteristics, and response to therapies. They are present in tumour tissues or body fluids and encompass a wide variety of molecules, including transcription factors, cell surface receptors, and secreted proteins. Effective tumour markers are in great demand since they have the potential to reduce cancer mortality rates by facilitating diagnosis of cancers at early stages and by helping to individualize treatments. During the last decade, improved understanding of carcinogenesis and tumour progression has revealed a large number of potential tumour markers. It is predicted that even more will be discovered in the near future with the application of current technologies such as tissue microarrays, antibody arrays, and mass spectrometry.
Interleukin-1 receptor accessory protein (IL1RAP) has previously been identified as cell-surface biomarker associated with haematological neoplastic disorders such as chronic myeloid leukemia (CML), acute myeloid leukemia (AML) and myelodysplatic syndromes (MDS) (for example, see WO 2011/021014 to Cantargia A B, Järås et al., 2010, Proc Natl Acad Sci USA 107(37):16280-5, Askmyr et al., 2013, Blood. 121(18):3709-13 and Barreyro et al., 2012, Blood 120(6):1290-8, the disclosures of which are incorporated herein by reference). More recently, the usefulness of IL1RAP as a diagnostic and therapeutic biomarker for solid tumours, such as melanomas, has also been revealed (see WO 2012/098407 to Cantargia AB, the disclosures of which are incorporated herein by reference).